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The Orion.js Logger is a powerful, flexible logging utility built on top of Winston. It provides structured logging capabilities with customizable formats, transports, and context tracking.

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Installation

pnpm add @orion-js/logger

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Basic Usage

import {logger} from '@orion-js/logger'

// Basic logging with different levels
logger.debug('Debug message', {customData: 'value'})
logger.info('Info message', {userId: 123})
logger.warn('Warning message', {attemptCount: 3})
logger.error('Error occurred', {error: new Error('Something went wrong')})

// Add metadata to all subsequent logs from this logger instance
const userLogger = logger.addMetadata({userId: 'user-123'})
userLogger.info('User action', {action: 'login'})

// Add context based on the current module
const contextLogger = logger.addContext(module)
contextLogger.info('Operation completed', {result: 'success'})

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Critical Logging Pattern

The first argument must always be a static string. All variables should be passed in the object as the second argument. 
// CORRECT - Static string first, variables in object
logger.info('User created successfully', {userId: user._id, email: user.email})
logger.warn('Rate limit approaching', {currentRate: rate, limit: maxRate})

// INCORRECT - Variables in the message string
logger.info(`User ${userId} created`) // DON'T DO THIS
logger.info('User ' + userId + ' created') // DON'T DO THIS
This pattern is required because:
  • Log aggregation tools can group logs by the static message
  • Searching logs by message becomes predictable
  • Variable data is properly indexed and queryable

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Error Logging Pattern

When logging errors, the error object must be in a parameter named error in the second argument object: 
try {
  await performOperation()
} catch (error) {
  // CORRECT - Error object in the 'error' property
  logger.error('Operation failed', {error, userId, operationType})

  // INCORRECT - Error as message or wrong property name
  logger.error(error.message) // DON'T DO THIS
  logger.error('Operation failed', {err: error}) // DON'T DO THIS
  logger.error('Operation failed: ' + error.message) // DON'T DO THIS
}
This ensures:
  • Stack traces are properly captured
  • Error serialization works correctly
  • Log analysis tools can extract error details

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Features

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Log Levels

The logger supports the standard log levels:
  • error: For error conditions
  • warn: For warning conditions
  • info: For informational messages
  • debug: For debugging information

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Automatic Contextual Information

Each log message automatically includes:
  • Timestamp
  • Log level
  • File name where the log was triggered (automatically detected)
  • OpenTelemetry trace and span IDs (when available)

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Formatting

The logger supports two main output formats:
  1. Text Format (for development):
    • Colorized output
    • Human-readable formatting
    • Activated when ORION_DEV=1 environment variable is set
  2. JSON Format (for production):
    • Structured JSON logs
    • Ideal for log aggregation and analysis
    • Default in production environments

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OpenTelemetry Integration

The logger automatically detects and includes OpenTelemetry trace and span IDs when available, enabling correlation between logs and traces.

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Advanced Configuration

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Setting Log Level

import {setLogLevel} from '@orion-js/logger'

// Set the minimum log level to display
setLogLevel('info') // Will show info, warn, and error logs, but not debug

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Adding Custom Transports

import {addTransport} from '@orion-js/logger'
import {transports} from 'winston'

// Add a file transport
const fileTransport = new transports.File({
  filename: 'application.log',
  level: 'info'
})

addTransport(fileTransport)

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Complete Logger Configuration

import {configureLogger} from '@orion-js/logger'
import {format, transports} from 'winston'

configureLogger({
  level: 'debug',
  format: format.combine(
    format.timestamp(),
    format.json()
  ),
  transports: [
    new transports.Console(),
    new transports.File({filename: 'combined.log'})
  ]
})

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Best Practices

  1. Use Static Message Strings: The first argument must be a static string for proper log aggregation: 
    // Good
logger.info('User created', {userId: '123', email: '[email protected]'})

// Avoid
logger.info(`User ${userId} created with email ${email}`)
  2. Pass Error Objects Correctly: Use the error property name: 
    try {
  await someOperation()
} catch (error) {
  // Good - preserves stack trace and uses correct property name
  logger.error('Operation failed', {error, context: 'user-service'})

  // Avoid
  logger.error('Operation failed', {message: error.message})
}
  3. Add Context: Use logger.addContext(module) at the top of your files to automatically include file information.
  4. Use Appropriate Levels:
    • debug: Detailed information useful during development
    • info: Normal application behavior, milestones
    • warn: Unexpected but handled issues
    • error: Errors that prevent proper operation
  5. Include Relevant Data: Pass structured objects with relevant context: 
    logger.info('Payment processed', {
  orderId: order._id,
  amount: payment.amount,
  currency: payment.currency,
  method: payment.method
})

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Common Patterns

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Service Logging

@Service()
export class ProcessPaymentService {
  async execute(orderId: OrderId, paymentData: PaymentData) {
    logger.info('Processing payment', {orderId, amount: paymentData.amount})

    try {
      const result = await this.paymentGateway.charge(paymentData)
      logger.info('Payment successful', {orderId, transactionId: result.id})
      return result
    } catch (error) {
      logger.error('Payment failed', {error, orderId, amount: paymentData.amount})
      throw error
    }
  }
}

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Migration Logging

@MigrationService({name: 'MigrateUsers.v1', useMongoTransactions: false})
export class MigrateUsers {
  async runMigration() {
    let processed = 0

    for await (const user of cursor) {
      await this.processUser(user)
      processed++

      // Log progress every 500 documents
      if (processed % 500 === 0) {
        logger.info('Migration progress', {processed, migrationName: 'MigrateUsers.v1'})
      }
    }

    logger.info('Migration complete', {processed, migrationName: 'MigrateUsers.v1'})
  }
}